1. Field of the Invention
The present invention relates to a supercharger mounted on the engine or and like, and specifically to a supercharger that has an electric motor for assisting turbine rotation of the supercharger in a low speed rotation range of an engine. More specifically, the present invention relates to a supercharger with an electric motor in which a power supplying connector for driving the electric motor can be made compact.
2. Description of Related Art
The supercharger is used, for example, for a high output of an automotive engine. In the supercharger, a turbine impeller of a turbine is rotated by exhaust energy of the engine, and the output of the turbine rotates a compressor impeller of a compressor. Thereby, a compressed air is supplied to the engine from the compressor to obtain a supercharged state in the engine in which the air intake is greater than natural air intake.
In the supercharger, the turbine hardly works in a low speed rotating region of the engine, due to a low exhaust flow rate from the engine. As a supercharger solving the problem, there is a supercharger with an electric motor in which the electric motor that assists acceleration of the supercharger is provided for improving a turbo effect in a low speed rotation range. For example, such a supercharger is disclosed in patent document 1 (patent document 1: Japanese Patent National Publication of translated version No. 2000-514897 “Motor Assisted Supercharger for Internal Combustion Engine”). The electric motor of the supercharger has, as an output shaft, a shaft coupling a turbine impeller and a compressor impeller. By this structure, the electric motor assists operation of the supercharger by receiving electric power from an outside of the supercharger.
FIG. 1 is a cross sectional view of a supercharger with an electric motor according to the related art. In FIG. 1, an electric motor 11 includes a rotor 11a provided in a shaft 5, and a stator 11b provided in an outer side in a radial direction from the rotor 11a. The rotor 11a is constituted by a plurality of permanent magnets arranged in a circumferential direction, and the stator 11b is constituted by a plurality of coils 17 arranged in the circumferential direction. In FIG. 1, there is arranged a power supply line 19 for supplying electric power to the electric motor 11. The power supply line 19 has one end portion connected to the stator 11b of the electric motor 11, and the other end portion connected to a connector 31. The connector 31 is provided in an outer circumferential surface of a bearing housing 6 to receive electric power. A terminal 28 supplying the electric power is connected to the connector 31.
The connector 31 in FIG. 1 is greatly affected by heat from the engine, and heat of an exhaust gas flowing within a turbine housing 7. In other words, the supercharger is exposed to a high-temperature ambient atmosphere. Accordingly, the connector 31 provided in an outer circumferential surface of the bearing housing 6 is required to stand such a high temperature. For this reason, a thickness of the outer wall of the connector 31 is increased for the purpose of increasing a heat insulating property between the inside and outside of the connector 31. As a result, the connector 31 is increased in size. Accordingly, since a supercharger main body is increased in size to such a degree and the weight thereof is increased, a mounting trouble can occur when mounting the supercharger on the engine.